RIO DE JANEIRO, May 23 (Reuters) - Brazilian striker Adriano, recalled for next month's World Cup qualifiers against Paraguay and Argentina, has now also been included in the squad for the warm-up friendlies against Canada and Venezuela.

The Brazilian Football Confederation (CBF) announced that Adriano, on loan to Sao Paulo from Inter Milan, would be in the squad to face Canada in Seattle on May 31 and Venezuela in Boston on June 6.

Adriano was freed for the two games after Sao Paulo were
knocked out of the Libertadores Cup by Fluminense on Wednesday.

He was initially called up last week for the World Cup
qualifiers away to Paraguay on June 15 and at home to Argentina
three days later.

It was only the second time the 26-year-old had been picked
by Brazil since the 2006 World Cup.

Adriano, plagued by physical and reported alcohol problems
last year with Inter Milan, has refound his form since joining
Sao Paulo on loan in December, scoring 16 goals in all
competitions.

Meanwhile, Brazil and AC Milan playmaker Kaka underwent surgery on his left knee on Friday and is doubtful for next month's World Cup qualifiers against Paraguay and Argentina.

Brazil team doctor Jose Luis Runco said the arthroscopy
operation had gone well but did not want to estimate how long
the World Player of the Year would be out of action.

'The result was very positive but I don't want to make a
prediction,' Runco said. 'The certainty is that he's
out of the friendlies. We'll think about the World Cup
qualifiers later.'

'We'll have a look every day. We're not going to jump the
gun so that he can play for the national team.'

Brazil face Canada in a friendly on May 31 and Venezuela on
June 6, both in the United States.

They are away to Paraguay in a World Cup qualifier on June
15 and at home to Argentina three days later.

Runco said Kaka had suffered damage to the meniscus caused
by overuse. 'It's like having a stone in your shoe,' he said.

On arriving at the Rio de Janeiro hospital for the
operation, Kaka told reporters: 'We've done everything possible
to avoid surgery but there's no way out.

'My thinking is that I will miss the friendlies but will be
ready for the World Cup qualifiers.'